What does "peer reviewed" mean?
To put it simply, it means that an article an author has written was reviewed by a group of their peers, meaning other academics in their field of study. Synonyms for peer reviewed journals are "scholarly" or "refereed" journals.
How do you know an article has been peer reviewed?
Not all journals are peer reviewed. You can determine if one has been peer reviewed in a few ways. Some journals simply say they are peer reviewed. If the journal does not say it, a list of editors (usually located around the masthead of the journal) is also a good indicator. You can also visit the journal's official website to locate a list of editors or a statement on whether or not it is peer reviewed.